JPH08147601A - Signal transmission device - Google Patents

Abstract

(57) [Summary] [Object] To provide a system capable of reducing the number of signal transmission paths inside and outside a rotating cylinder. [Structure] During recording, input video signals, audio signals, and control signals are frequency-multiplexed to input terminals 1 to 3 and transmitted to a rotary cylinder RS via a bidirectional transmission circuit 5. After this signal is separated and demodulated, the video / audio signal is recorded / reproduced by the recording / reproducing circuit 7.
Recording is performed by driving the magnetic heads 8a to 8d via a and 7b. The control signal is used for switching the switches in the recording / reproducing circuits 7a and 7b. During reproduction, magnetic heads 8a-8d
The video and audio signals from the recording / reproducing circuits 7a and 7b
And frequency-multiplexing is carried out via the bidirectional transmission circuit 5 and is transmitted to the outside of the rotary cylinder RS. This signal is separated and demodulated, and then video and audio signals are output from the output terminals 11 and 12. The control signal is transmitted to the rotary cylinder RS via the bidirectional transmission circuit 5, and is used for switching the switches in the recording / reproducing circuits 7a and 7b as in the recording. During reproduction, the bidirectional transmission circuit 5 simultaneously transmits bidirectionally the control signal and the output of the reproduction signal multiplexing circuit 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helical scan system which supplies a control signal to a rotary cylinder having a plurality of magnetic heads and head amplifiers, and a switch circuit for switching the magnetic heads to switch the switch circuits. The present invention relates to a signal transmission device in a magnetic recording / reproducing device or the like.

[0002]

2. Description of the Related Art In a helical scan type magnetic recording / reproducing apparatus such as a VTR, it is common to arrange a recording / reproducing amplifier outside a rotary cylinder to perform signal transmission with a magnetic head via a rotary transformer. Is.

In recent years, the number of rotary heads has increased due to the adoption of systems such as HiFi voice, narrow, and flying erase. For this reason, the above method requires as many rotary transformers as the number of magnetic heads, resulting in an increase in cost.

Therefore, a system as shown in FIG. 12 is conceivable in which the number of rotary transformers can be reduced by mounting a recording amplifier, a reproducing amplifier, etc. in the rotary cylinder and switching signals in the rotary cylinder. There is.

The recording / reproducing operation of this system will be described. Since an audio signal is recorded / reproduced on the same path as a video signal, only the video signal will be described here. That is, at the time of recording, the recording video signal input terminal 6
The recording video signal input from the No. 1 is amplified by the recording amplifier 63a in the interface circuit 63 and then transmitted to the rotary cylinder via the video rotary transformer 64a. This signal is turned on during recording in the recording / reproducing circuit 65.
Recording is performed by driving the video magnetic heads 66a and 66b via the switches 65a and 65b.

During reproduction, the magnetic head 66 for video is used.
After the reproduced video signals reproduced from a and 66b are amplified by the reproduction amplifiers 65c and 65d in the recording / reproduction circuit 65, a desired signal is selected by the switch 65e, and the outside of the rotary cylinder via the image rotary transformer 64a. To transmit.
The amplifier 63b of the interface circuit 63 receives this signal and outputs it from the reproduced video signal output 62.

Here, the switches 65a, 65b, 65e
A control signal for switching control is input from the control signal input terminal 69, frequency-modulated by the modulation circuit 70, and then transmitted into the rotary cylinder via the control rotary transformer 64c. After demodulating this signal by the demodulation circuit 71, it is taken out from the control signal output terminal 72 and used for controlling each switch.

However, in such a system,
Since the transmission between the inside and the outside of the rotary cylinder is performed by using a three-channel rotary transformer, there is a problem that the cost increase cannot be ignored.

[0009]

The above-mentioned conventional signal transmission device has a problem that the increase in cost due to the three-channel rotary transformer cannot be ignored in recent years when thorough cost reduction is required.

It is an object of the present invention to provide a system capable of minimizing the signal transmission path required for signal transmission inside and outside the rotary cylinder.

[0011]

In order to solve the above problems, the present invention has means for multiplexing and transmitting video, audio and control signals during recording. Alternatively, a means for multiplexing and transmitting the video and control signals is provided. During reproduction, a control signal is transmitted to the inside of the rotary cylinder, and a video signal and an audio signal are transmitted to the outside of the rotary cylinder, so that means for bidirectionally transmitting the rotary transformer of one channel is provided.

[0012]

When the video signal, the audio signal and the control signal are multiplexed and transmitted by the above means, the signal transmission between the inside and the outside of the rotary cylinder can be performed by the rotary transformer having only one channel, so that the cost of the rotary transformer is reduced. Can be reduced. Further, in the case of multiplexing and transmitting the video and control signals, the rotary transformer can be reduced to 2 channels in the HiFi model, and the rotary transformer can be reduced to 1 channel by using the same system in the normal audio model.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a system diagram for explaining an embodiment of the present invention. In this embodiment, a video signal, an audio signal and a control signal are multiplexed and transmitted. In FIG. 1, at the time of recording, the recording video signal, the recording audio signal, and the control signal, which are respectively input to the input terminals 1 to 3, are frequency-converted as necessary by the recording signal multiplexing circuit 4, and then frequency multiplexing is performed. , Bidirectional transmission circuit 5
To the rotary cylinder RS. This signal is
After the signals are separated by the recording signal separation circuit 6 and demodulated as necessary, the recording video signal and the recording audio signal are respectively transferred via the recording / reproducing circuits 7a and 7b to the video magnetic heads 8a and 8b and the audio signal. Magnetic heads 8c, 8d
To record. The control signal is the recording / reproducing circuit 7
It is used for switching the switches in a and 7b. Here, as the recording / reproducing circuits 7a and 7b, for example, circuits similar to the conventional example are used.

During reproduction, the magnetic head 8a for video,
8b, reproduced video signals and reproduced audio signals from the magnetic heads 8c and 8d for audio are respectively recorded / reproduced by the recording / reproducing circuit 7
The signal is input to the reproduction signal multiplexing circuit 9 via a and 7b, where frequency conversion is performed if necessary, frequency multiplexing is performed, and the signal is transmitted to the outside of the rotary cylinder via the bidirectional transmission circuit 5.
This signal is separated by the reproduction signal separation circuit 10, demodulated as necessary, and then output from the reproduction video signal output terminal 11 and the reproduction audio signal output terminal 12.
At this time, the control signal is transmitted to the rotary cylinder RS through the bidirectional transmission circuit 5 through the same transmission path as that at the time of recording, and for switching the switches in the recording / reproducing circuits 7a and 7b as at the time of recording. To use. During reproduction, the bidirectional transmission circuit 5 simultaneously transmits bidirectionally the control signal and the output of the reproduction signal multiplexing circuit 9.

In this system, the bidirectional transmission circuit 5 is
Since only a circuit needs to be used, signal transmission is possible with a 1-channel rotary transformer.

FIG. 2 shows the embodiment of FIG. 1 in more detail. The recording / reproducing circuits 7a and 7b and the magnetic heads 8a to 8d in the embodiment of FIG.
For example, since the same circuit as the conventional example can be used,
It is omitted in each figure after FIG.

The operation of FIG. 2 will be described. When recording,
The recording voice signal input from the input terminal 2 is supplied to the modulation circuit 4
The control signal modulated by a and input from the input terminal 3 is modulated by the modulation circuit 4b. The outputs of the modulation circuits 4a and 4b and the recording video signal input from the input terminal 1 are added by the addition circuit 4c, and frequency multiplexing is performed here. After that, input to the drive amplifier 5a of the bidirectional transmission circuit 5,
By driving the rotary transformer 5b, it is transmitted into the rotary cylinder RS. The recording video signal is separated from the frequency-multiplexed signal by the filter 6a, and the recording video signal is output from the output terminal 13. Further, the frequency-multiplexed signal separates the recording voice signal modulated by the filter 6b,
After demodulation by the demodulation circuit 6d, a recording audio signal is output from the output terminal 14. The recorded video signal and the recorded audio signal are input to the recording / reproducing circuits 7a and 7b in FIG. 1 and magnetically recorded. Further, the frequency-multiplexed signal is separated from the control signal modulated by the filter 6c to separate it from the demodulation circuit 6e.
After demodulating with, the control signal is output from the output terminal 15. This control signal corresponds to the recording / reproducing circuits 7a and 7b shown in FIG.
It is used for switching control of each switch inside.

Further, at the time of reproduction, the recording / reproducing circuit 7 shown in FIG.
The reproduced audio signal output from b is input to the modulation circuit 9a from the input terminal 17 and is modulated there, and the recording / recording of FIG.
The reproduction video signal output from the reproduction circuit 7a is added by the addition circuit 9b to perform frequency multiplexing. Then, the signal is input to the drive amplifier 5c of the bidirectional transmission circuit 5 and is driven outside the rotary cylinder RS by driving the rotary transformer 5b. A reproduction video signal is separated from the frequency multiplexed signal by the filter 10a, and the reproduction video signal is output from the output terminal 11. In addition, filter 1 from the frequency-multiplexed signal
The reproduced voice signal modulated by 0b is separated and the demodulation circuit 10
After demodulated by c, the reproduced voice signal is output from the output terminal 12. At this time, the control signal is as described in FIG.
Data is transmitted to the inside of the rotary cylinder via the bidirectional transmission circuit 5 through the same transmission path as that used for recording. Therefore, in the bidirectional transmission circuit 5, during reproduction, the control signal and the output of the adder circuit 9b simultaneously perform bidirectional transmission.

Here, an outline of the frequency band of each signal transmitted through the rotary transformer is as shown in FIG. 3, for example. In FIG. 3, for example, in the VHS system VTR, the video signal band a is an FM signal of several tens of kHz to several MHz and the audio band b.
Is a 2-channel HiFi voice, and is a narrow band FM signal of 1.3 MHz + 1.7 MHz in the NTSC system. Further, the control signal band c needs to have a band capable of transmitting a switching signal of, for example, about 30 Hz in order to switch out signals from a pair of magnetic heads facing each other at the time of reproduction to extract a continuous reproduction signal. For example, after being frequency-multiplexed in FIG. 2, the video signal band remains unchanged as shown in FIG. 3D, and the audio signal and control signal modulated in the high frequency band are multiplexed.

Here, the heights of the modulation bands of the voice signal and the control signal may be reversed. As for the modulation method, FM
The same applies to modulation, PM modulation, and AM modulation. In this example, the control signal is modulated in the high frequency band of the video signal, but since the control signal band is originally narrow, it may be possible to multiplex without modulation. In this case, it is difficult to separate the video signal and the control signal, but the modulation / demodulation circuit for the control signal can be omitted. Further, in the above example, it was explained that the transmission between the inside and outside of the rotary cylinder is performed via the rotary transformer, but, for example, signal transmission via a slip ring or optical transmission via a photoelectric conversion means is also conceivable.

The present embodiment is characterized in that signals for transmission inside and outside the rotary cylinder are frequency-multiplexed with each other through a signal transmission means such as a rotary transformer and are transmitted in one channel. Therefore, the means for frequency multiplexing is not limited to the above embodiment.

FIG. 4 is a system diagram for explaining another embodiment of the present invention. In this embodiment, the recording audio signal input to the input terminal 2 and the control signal input to the input terminal 3 are added by the adder circuit 4d, and the signal modulated by the modulator circuit 4e is further input to the input terminal 1. The added recording video signal is added by the adder circuit 4f to the drive amplifier 5
Filter 6 from the part input to a and the rotary cylinder RS
f, through the demodulation circuit 6g, one part is supplied to the filter 6b which outputs to the output terminal 14 as a recording audio signal, and the other part is supplied to the filter 6c which outputs to the output terminal 15 as a control signal, which is different from the configuration of FIG.

At the time of recording, the recording audio signal input from the input terminal 2 and the control signal input from the input terminal 3 are added by the adding circuit 4d and then modulated by the modulating circuit 4e. The output of the modulation circuit 4e and the recording video signal input from the input terminal 1 are added by the addition circuit 4f to frequency-multiplex these signals. After that, the signal is input to the drive amplifier 5a of the bidirectional transmission circuit 5, and is transmitted to the rotary cylinder RS by driving the rotary transformer 5b. The recording video signal is separated from the frequency-multiplexed signal by the filter 6a, and the recording video signal is output from the output terminal 13. Also, from the frequency-multiplexed signal, the filter 6f is used to modulate the modulation circuit 4e.
Output is separated and demodulated by the demodulation circuit 6g, then the recording audio signal is separated by the filter 6b, and the recording audio signal output terminal 1
The recording voice signal is output from 4. The filter 6c separates the control signal and outputs the control signal from the output terminal 15. It should be noted that the reproduction is the same as that shown in FIG.

In the case of this embodiment, since the recording voice signal and the control signal are added and then modulated, there is an advantage that the modulation circuit and the demodulation circuit can be shared.

FIG. 5 is a system diagram for explaining a second other embodiment of the present invention. This embodiment is similar to the system shown in FIG. 2, except that in the embodiment shown in FIG. 2, an audio signal is modulated and frequency-multiplexed, whereas in this embodiment, a video signal is modulated and frequency-multiplexed. That is,
In a different configuration, the recording video signal input to the input terminal 1 is added to the addition circuit 4c via the modulation circuit 4g, and the recording audio signal input to the input terminal 2 is added to the addition circuit 4c. The reproduced video signal input to the output terminal 11 is input to the filter 10a via the demodulation circuit 10d, and the reproduced audio signal input to the output terminal 12 is input to the filter 10b. The output of the filter 6a is input to the output terminal 13 through the demodulation circuit 6h, and the input terminal 1 to which the reproduced video signal is input.
The input terminal 17 to which the reproduced audio signal is input via the modulation circuit 9c is directly input to the addition circuit 9b.

As a result, the lowest frequency of the signal transmitted by the rotary transformer RS is determined by the audio signal band, and there is an advantage that the lowest frequency for signal transmission becomes higher than that of the embodiment of FIG. This is because, for example, when the rotary transformer RS is driven by voltage, the impedance in the signal band of the transformer becomes high, so that the drive current can be made small.

FIG. 6 is a system diagram for explaining a third other embodiment of the present invention. Input terminal 1 when recording
The recording video signal input from the input terminal 3 and the control signal input from the input terminal 3 are added by the addition circuit 4h, and then the modulation circuit 4h is added.
Modulate with i. Frequency multiplexing is performed by adding the output of the modulation circuit 4i and the recording audio signal input from the input terminal 2 by the addition circuit 4j. The frequency-multiplexed signal is input to the drive amplifier 5a of the bidirectional transmission circuit 5,
It is transmitted to the rotary cylinder RS by driving the rotary transformer 5b.

The recorded voice signal is separated from the frequency multiplexed signal by the filter 6b, and the recorded voice signal is output from the output terminal 14. The output of the modulation circuit 4i is separated from the frequency-multiplexed signal by the filter 6i, demodulated by the demodulation circuit 6j, the recording video signal is separated by the filter 6a, and the recording video signal is output from the output terminal 13. Further, the control signal is separated from the frequency multiplexed signal by the filter 6c, and the control signal is output from the output terminal 15.

Incidentally, since the processing at the time of reproduction is the same as that of FIG. 5, the description thereof is omitted here.

In the case of this embodiment, since the recording video signal and the control signal are added and then modulated, the modulation circuit and the demodulation circuit can be shared as in the embodiment of FIG. 4, and the circuit scale can be reduced. Become.

FIG. 7 is a system diagram for explaining a fourth other embodiment of the present invention. This system is also similar to the embodiment of FIG. 2, but in the embodiment of FIG. 2, the video signal is transmitted in the same band, but in this embodiment, the video signal is also modulated and frequency-multiplexed. In the case of this embodiment, since the frequency band of the signal transmitted through the rotary transformer can be set completely freely, the degree of freedom in design becomes extremely large.

In this system, since the signal transmission between the inside and the outside of the rotary cylinder can be performed by the rotary transformer having only one channel, the cost of the rotary transformer can be reduced.

FIG. 8 is a system diagram for explaining a fifth other embodiment of the present invention. This is an embodiment in the case where a means for multiplexing and transmitting a video signal and a control signal is provided.

That is, the recording video signal input to the input terminal 21 and the control signal input to the input terminal 22 are input to the recording signal multiplexing circuit 23, where frequency conversion is performed and frequency multiplexing is performed. The frequency-multiplexed signal is transmitted into the rotary cylinder RS via the bidirectional transmission circuit 24. This signal is separated into each signal and demodulated in the recording signal separation circuit 25. The recording video signal is magnetically recorded by driving the video magnetic heads 27a and 27b via the recording / reproducing circuit 26. The control signal is used for switching switches in the recording / reproducing circuit 26. Here, as the recording / reproducing circuit 26, for example, a circuit similar to the conventional example is used.

At the time of reproduction, the magnetic head 27 for video is used.
The recording / reproducing circuit 26 reproduces the reproduced video signals from a and 27b.
And to the outside of the rotary cylinder RS via the bidirectional transmission circuit 24. This signal is separated by a reproduction signal separation circuit 28 and then output from an output terminal 29 for outputting a reproduction video signal. At this time, the control signal is transmitted into the rotary cylinder RS via the bidirectional transmission circuit 24 through the same transmission path as that used for recording, and is used for switching the switches in the recording / reproducing circuit 26 as in the case of recording. . Therefore, in the bidirectional transmission circuit 24, the control signal and the reproduced video signal are simultaneously bidirectionally transmitted during reproduction.

As described above, when the video signal and the control signal are multiplexed and transmitted, the rotary transformer can be reduced to two channels in the HiFi model. Moreover, if the same system is used for a normal voice model, it is not necessary to transmit a voice signal into the rotary cylinder RS, so the rotary transformer can be reduced to one channel. Sharing the same system among different models is a great advantage from the standpoint of standardization.

FIG. 9 shows the embodiment of FIG. 8 in more detail. Note that the recording / reproducing circuit 26 and the magnetic heads 27a and 27b in the embodiment of FIG. 8 can use the same circuits as those of the conventional example, and are therefore omitted in FIG.

The operation of this system will be described. At the time of recording, the control signal input from the control signal input terminal 22 is modulated by the modulation circuit 23a, and the recording video signal terminal 21
Frequency multiplexing is performed by adding the recorded video signal input from the adder 23b in the adder circuit 23b. The frequency-multiplexed signal is input to the drive amplifier 24a of the bidirectional transmission circuit 24, and the rotary transformer 24b is driven to be transmitted into the rotary cylinder. The recorded video signal is separated from the frequency multiplexed signal by the filter 25a, and the recorded video signal is output from the recorded video signal output terminal 30. This recorded video signal is input to the recording / reproducing circuit 26 of FIG. 8 and magnetically recorded.

The frequency-multiplexed signal is separated from the control signal modulated by the filter 25b to demodulate the circuit 25c.
After demodulating by, the control signal is output from the output terminal 31. This control signal is used for switching control of each switch in the recording / reproducing circuit 26 of FIG.

At the time of reproduction, the reproduction video signal output from the recording / reproduction circuit 26 of FIG. 8 is input to the drive amplifier 24c of the bidirectional transmission circuit 24, and the rotary transformer 24 is supplied.
It is transmitted to the outside of the rotary cylinder RS by driving b. Then, the playback video signal is taken out by the filter 28a,
The reproduced video signal is output from the reproduced video signal output terminal 29. At this time, as described with reference to FIG. 8, the control signal is transmitted to the inside of the rotary cylinder RS via the bidirectional transmission circuit 24 through the same transmission path as at the time of recording. Therefore, the bidirectional transmission circuit 2
In No. 4, the control signal and the reproduced video signal are simultaneously transmitted in both directions during reproduction.

The modulation of the control signal is performed by, for example, FM, PM, A
Any modulation method of M may be used. Although the control signal is modulated in this embodiment, as shown in FIG. 3, since the control signal band is narrow, it may be possible to multiplex without modulating. In this case, it is difficult to separate the video signal and the control signal, but the modulation / demodulation circuit for the control signal can be omitted.

FIG. 10 is a circuit configuration diagram for specifically explaining the bidirectional transmission circuit used in each of the above embodiments.
The bidirectional transmission circuit needs to perform bidirectional transmission of the control signal, the reproduced video signal, and the reproduced audio signal at the same time during reproduction.

In FIG. 10, the first input signal input from the input terminal 41 is converted into a current by the current drive amplifier 42 and input to the first terminal 43a of the rotary transformer 43. The winding ratio of the rotary transformer 43 is 1: 1.
Then, if the coupling coefficient is 1, the same current flows through the second terminal 43b. At this time, the amplifier 44a, the transistor 44b,
Due to the current source 44c, the second terminal 43b of the rotary transformer 43 has a low impedance, and the signal current is taken out from the collector of the transistor 44b. This signal is voltage-converted by the resistor 45 and is output from the output terminal 47.

Further, the second input signal inputted from the input terminal 48 is inputted to the non-inverting input of the amplifier 44a, and the amplifier 44a, the transistor 44b and the current source 44c cause the voltage of the second terminal 43b of the rotary transformer 43. drive. At this time, since the same voltage as the second terminal 43b is generated at the first terminal 43a of the rotary transformer 43,
This voltage can be taken out from the output terminal 50 by the amplifier 49.

By using such a circuit, it is possible to simultaneously perform current transmission in one direction and voltage transmission in the opposite direction of the rotary transformer. Since the rotary transformer is an inductive load, its impedance decreases in the low frequency range. For this reason, for example, in the case of voltage driving, the driving current becomes larger as the signal in the low frequency range increases. It goes without saying that this is disadvantageous in terms of circuit configuration.

Therefore, when the voltage transmission and the current transmission are simultaneously performed by the bidirectional transmission circuit, it is advantageous in terms of circuit configuration to drive a signal having a lower frequency component with the current. For example, in the case of the embodiment of FIG. 2, the control signal may be voltage-transmitted. That is, the reproduced video signal and the reproduced audio signal may be input from the input terminal 41, and the control signal may be input from the input terminal 48.

In this case, at the time of recording, the recording video signal and the recording audio signal are also voltage-transmitted from the input terminal 48, but the current transmission circuit portion of FIG. 10 is provided in the opposite direction, and the circuit is switched for recording and reproduction. By switching the recording and recording signals, it is possible to current-transmit the recording video signal and the recording audio signal. At this time, the control signal is current transmission during recording and voltage transmission during reproduction.

FIG. 11 is a circuit configuration diagram for explaining another specific example of the bidirectional transmission circuit. That is, when the first input signal input from the input terminal 41 is converted into a current by the current drive amplifier 42 and is input to the first terminal 43a of the rotary transformer 43, the winding ratio of the rotary transformer is 1 :. 1, the coupling coefficient is 1 and the resistance is 45,
If 50 is the same, ½ of the signal current flows through both resistors. In addition, when the second input signal input from the input terminal 48 is converted into a current by the current drive amplifier 49 and is input to one end of the second terminal 43b of the rotary transformer 43, the signal current flows through the resistors 45 and 50. 1/2 of each flow.

Therefore, the voltage generated across the resistors 45 and 50 is
It is the sum of the first and second input signals. Therefore, if the output voltages of the output terminal 47 and the output terminal 52 are frequency-separated using a filter, only a desired signal can be extracted. By using such a circuit, it is possible to simultaneously perform current transmission in both directions of the rotary transformer.

As described above, by using these bidirectional transmission circuits, it is possible to transmit signals bidirectionally at the same time by using only the 1-channel rotary transformer.

[0051]

As described above, according to the bidirectional transmission device of the present invention, video, audio, and control signals are multiplexed so that signal transmission between the inside and the outside of the rotary cylinder is performed by only one channel. Since it can be performed by a rotary transformer, the cost can be reduced. Also, by multiplexing video and control signals, the rotary transformer can be reduced to 2 channels in the HiFi model, and the rotary transformer can be reduced to 1 channel by using the same system in the normal audio model.

[Brief description of drawings]

FIG. 1 is a system diagram for explaining an embodiment of the present invention.

FIG. 2 is a system diagram for explaining FIG. 1 more specifically.

FIG. 3 is an explanatory diagram for explaining frequency allocation of each signal used in FIG. 1.

FIG. 4 is a system diagram for explaining another embodiment of the present invention.

FIG. 5 is a system diagram for explaining a second other embodiment of the present invention.

FIG. 6 is a system diagram for explaining a third embodiment of the present invention.

FIG. 7 is a system diagram for explaining a fourth other embodiment of the present invention.

FIG. 8 is a system diagram for explaining a fifth other embodiment of the present invention.

FIG. 9 is a system diagram for explaining FIG. 8 more specifically.

FIG. 10 is a circuit configuration diagram for explaining a specific example of a bidirectional transmission circuit used in each embodiment of the present invention.

FIG. 11 is a circuit configuration diagram for explaining another specific example of the bidirectional transmission circuit used in each embodiment of the present invention.

FIG. 12 is a system diagram for explaining a conventional signal transmission device.

[Explanation of symbols]

1-3, 16, 17, 17, 21, 22, 32 ... Input terminals,
4, 23 ... Recording signal multiplex circuit, 5, 24 ... Bidirectional transmission circuit, 6, 25 ... Recording signal separation circuit, 7a, 7b, 26 ...
Recording / reproducing circuit, 8a to 8d, 27a, 27b ... Magnetic head, 9 ... Reproducing signal multiplexing circuit, 10, 28 ... Reproducing signal separating circuit, 11-15, 29, 30, 31, ... Output terminals, 4
a, 4b, 4e, 4g, 4i, 9a, 9c, 23a ... Modulation circuit 4c, 4d, 4f, 4h, 4j, 9b, 23b
... Adder circuit, 5a, 5c, 24a, 24c ... Drive amplifier, 5b, 24b ... Rotary transformer, 6a, 6
b, 6c, 6f, 6j, 10a, 10b, 25a, 25
b, 28a ... Filter, 6d, 6e, 6g, 6h, 6
j, 10c, 10d, 25c ... Demodulation circuit, RS ... Rotating cylinder.

Claims (15)

[Claims] 1. A helical scan type magnetic recording / reproducing apparatus equipped with a reproducing amplifier for amplifying signals from a plurality of magnetic heads in a rotary cylinder, for recording or reproducing through the magnetic head. Means for modulating at least one of the video signal and the audio signal into a frequency band different from the frequency band for recording via the magnetic head, and frequency-multiplexing with a control signal including a selection signal of the reproduction amplifier. A signal transmission device comprising: a signal transmission unit that transmits the frequency-multiplexed video, audio, and control signals by one channel. 2. A control signal including a selection signal of the reproduction amplifier is transmitted to the rotary cylinder during recording and reproduction,
The signal transmission device according to claim 1, wherein the video signal and the audio signal are transmitted to the inside of the rotary cylinder during recording and to the outside of the rotary cylinder during reproduction. 3. A helical scan type magnetic recording / reproducing apparatus equipped with a reproducing amplifier for amplifying signals from a plurality of magnetic heads in a rotary cylinder, wherein at least one of a recording video signal and a recording audio signal. A first signal multiplexing unit that modulates one of the signals into a frequency band different from a frequency band recorded via the magnetic head and frequency-multiplexes with a control signal including a selection signal of the reproduction amplifier; Bidirectional transmission means for transmitting the output of the multiplexing means from the fixed side of the rotary cylinder to the rotary side, and the recording video signal, the recording audio signal, and the control signal output to the rotary side of the rotary cylinder are separated from each other. First signal separating means for extracting, and at least one of the reproduced video signal and the reproduced audio signal, via the magnetic head. Second signal multiplexing means for performing frequency multiplexing by modulating to a frequency band different from the frequency band to be recorded, and reproduced video signal and reproduced sound from the output of the second signal multiplexing means transmitted to the fixed side of the rotary cylinder. A signal transmission device comprising a second signal separating means for separating a signal and extracting the separated signal. 4. A helical scan type magnetic recording / reproducing apparatus having a reproducing amplifier for amplifying signals from a plurality of magnetic heads in a rotary cylinder, wherein a control signal including a selection signal of the reproducing amplifier is modulated. First modulating means for controlling the recording audio signal, second modulating means for modulating the recording audio signal during recording, first adding means for adding the modulated control signal and recording audio signal to the recording video signal during recording, Bidirectional transmission means for transmitting the output of the first adding means to the rotating side of the rotary cylinder during recording, and transmitting only the output of the first modulating means to the fixed side of the rotating cylinder for reproducing; First, second and third selected and extracted the modulated control signal, the recording video signal and the modulated recording audio signal output from the rotating side, respectively. And signal selection means, first obtain the control signal and the recording audio signal outputs each demodulation of the first and third signal selecting means 1
And a second demodulating means, a third modulating means for modulating a reproduced audio signal during reproduction, a second adding means for adding the modulated reproduced audio signal to a reproduced video signal, and the bidirectional transmission during reproduction. Fourth and fifth signal selecting means for selecting and extracting the reproduced video signal and the modulated reproduced audio signal from the output of the second adding means transmitted to the fixed side of the rotary cylinder of the means, And a third demodulation means for demodulating the output of the fifth signal selection means to obtain the reproduced voice signal. 5. A helical scan type magnetic recording / reproducing apparatus equipped with a reproducing amplifier for amplifying signals from a plurality of magnetic heads in a rotary cylinder, and a control signal including a selection signal of the reproducing amplifier at the time of recording. Is added to the recording audio signal, a first modulating means for modulating the output of the first adding means, and a second adding means for adding the output of the first modulating means to the recorded video signal. And an output of the second adding means at the time of recording to the rotation side of the rotary cylinder, and at the time of reproduction, only the control signal is modulated by the first modulating means to output the output on the rotation side of the rotary cylinder. And a first and second signal for selectively extracting the output of the first modulator output from the rotation side of the rotary cylinder and the recorded video signal. Selecting means, first demodulating means for demodulating the output of the first signal selecting means to obtain the output of the second adding means, and selecting the control signal and the recorded audio signal from the output of the demodulating means Third and fourth signal selecting means for extracting the reproduced audio signal, second modulating means for modulating the reproduced audio signal during reproduction, and third adding means for adding the modulated reproduced audio signal to the reproduced video signal, The fifth and sixth reproduction video signals and the modulated reproduction audio signal are selected and extracted from the output of the third adding means transmitted to the fixed side of the rotary cylinder of the bidirectional transmission means during reproduction. And a second demodulation means for demodulating the output of the sixth signal selection means to obtain the reproduced audio signal. 6. A helical scan type magnetic recording / reproducing apparatus provided with a reproducing amplifier for amplifying signals from a plurality of magnetic heads in a rotary cylinder, wherein a control signal including a selection signal of the reproducing amplifier is modulated. First modulation means for modulating the recorded video signal at the time of recording, and first addition means for adding the modulated control signal and the modulated recorded video signal to the recorded audio signal at the time of recording Means for transmitting the output of the first adding means into the rotary cylinder during recording, and transmitting only the output of the first modulating means into the rotary cylinder during reproducing, the rotary cylinder First, second, and third signal selections for selecting and extracting the modulated control signal, the recording audio signal, and the modulated recording video signal from the rotation side of First obtaining the stage, the control signal and the recording video signal output each demodulation of the first and third signal selecting means
And second demodulating means, third modulating means for modulating the reproduced video signal during reproduction, second adding means for adding the modulated reproduced video signal to the reproduced video signal, and the bidirectional transmission during reproduction. From the output of the second adding means transmitted to the fixed side of the rotary cylinder via means,
Fourth and fifth signal selecting means for selecting and extracting the reproduced audio signal and the modulated reproduced video signal respectively, and a third for demodulating the output of the fifth signal selecting means to obtain the reproduced video signal. And a demodulation means for the signal transmission device. 7. A helical scan type magnetic recording / reproducing apparatus equipped with a reproducing amplifier for amplifying signals from a plurality of magnetic heads in a rotary cylinder, wherein a control signal including a selection signal of the reproducing amplifier is recorded. Sometimes a first adding means for adding the recorded video signal, a first modulating means for modulating the output of the first adding means, and a second adding means for adding the output of the first modulating means with the recorded audio signal. Adder means: The output of the second adder means is transmitted to the rotation side of the rotary cylinder at the time of recording, only the control signal is modulated by the first modulator means at the time of reproduction, and the output is fixed to the rotary cylinder. A two-way transmission means for transmitting to the side, and a first selection means for extracting the output of the first modulation means and the recorded audio signal from the rotation side of the rotary cylinder
And second signal selecting means, first demodulating means for demodulating the output of the first signal selecting means to obtain the output of the second adding means, and the control from the output of the first demodulating means. Third and fourth signal selecting means for selecting and extracting a signal and the recorded video signal, second modulating means for modulating the reproduced video signal at the time of reproduction, and adding the modulated reproduced video signal to the reproduced audio signal. From the output of the third adding means, which is transmitted to the fixed side of the rotary cylinder via the bidirectional transmission means during reproduction,
Fifth and sixth signal selecting means for selecting and extracting the reproduced audio signal and the modulated reproduced video signal respectively, and a second for demodulating the output of the sixth signal selecting means to obtain the reproduced video signal. And a demodulation means for the signal transmission device. 8. A helical scan type magnetic recording / reproducing apparatus having a reproducing amplifier for amplifying signals from a plurality of magnetic heads in a rotary cylinder, wherein a control signal including a selection signal of the reproducing amplifier is modulated. First modulating means, second and third modulating means for respectively modulating a recording video signal and a recording audio signal during recording, and the modulated control signal, the modulated recording video signal and the modulation during recording First for adding recorded audio signals
And the bidirectional transmission means for transmitting the output of the first adding means to the rotating side of the rotary cylinder at the time of recording and transmitting only the output of the first modulating means to the fixed side of the rotating cylinder at the time of reproducing. A first selected and extracting the modulated control signal, the modulated recording video signal, and the modulated recording audio signal obtained at the output of the rotary cylinder of the bidirectional transmission means on the rotating side. First and second and third signal selecting means, and first and second output signals of the first, second and third signal selecting means are demodulated to obtain the control signal, the recording video signal and the recording audio signal, respectively. Second and third demodulating means, fourth and fifth modulating means for respectively modulating the reproduced video signal and the reproduced audio signal during reproduction, and adding the modulated reproduced video signal and the modulated reproduced audio signal. A second adding means for, from the output of said second adding means is transmitted through said bi-directional transmission means at the time of reproduction on the fixed side of the rotary cylinder,
Fourth and fifth signal selecting means for selecting and extracting the modulated reproduced video signal and the modulated reproduced audio signal, respectively, and demodulating the outputs of the fourth and fifth signal selecting means, respectively. Fourth for obtaining a reproduced video signal and the reproduced audio signal
And a fifth demodulation means. 9. A helical scan type magnetic recording / reproducing apparatus equipped with a reproducing amplifier for amplifying signals from a plurality of magnetic heads in a rotary cylinder, for recording or reproducing through the magnetic head. And a control signal including a selection signal of the reproduction amplifier is frequency-multiplexed, and the video signal and the control signal are transmitted through a signal transmission unit of one channel. Signal transmission equipment. 10. A control signal including a selection signal of the reproduction amplifier is always transmitted to the rotary cylinder, and a video signal is
10. The signal transmission device according to claim 9, wherein the signal is transmitted to the rotating side of the rotary cylinder during recording and is transmitted to the fixed side of the rotating cylinder during reproduction. 11. A helical scan type magnetic recording / reproducing apparatus including a reproducing amplifier for amplifying signals from a plurality of magnetic heads in a rotary cylinder, including a recording video signal and a selection signal of the reproducing amplifier. The signal multiplexing means for frequency-multiplexing the control signal, the bidirectional transmission means for transmitting the output of the signal multiplexing means to the rotation side of the rotary cylinder, and the recording from the output of the rotation cylinder rotation side of the bidirectional transmission means First signal separation means for separating and extracting the video signal and the control signal respectively, and a reproduction video signal is transmitted to the fixed side of the rotary cylinder via the bidirectional transmission means, and the bidirectional transmission means is rotated. A signal transmission device comprising: second signal separating means for separating and reproducing the reproduced video signal from the output on the fixed side of the cylinder. 12. A helical scan type magnetic recording / reproducing apparatus including a reproducing amplifier for amplifying signals from a plurality of magnetic heads in a rotary cylinder, wherein a control signal including a selection signal of the reproducing amplifier is modulated. First adding means for adding, the first adding means for adding the modulated control signal to the recording video signal at the time of recording, and the output of the first adding means for transmitting at the rotating side of the rotary cylinder. , A bidirectional transmission means for transmitting only the output of the first modulation means to the fixed side of the rotary cylinder during reproduction, and the modulated control signal and the recorded video from the rotary side of the rotary cylinder of the bidirectional transmission means. First and second signal selecting means for selecting and extracting signals respectively, and a first demodulating means for demodulating an output of the first signal selecting means to obtain the control signal. And a third signal selecting means for selecting and extracting the reproduced video signal from the reproduced video signal transmitted to the fixed side of the rotary cylinder through the bidirectional transmission means during reproduction. Signal transmission equipment. 13. The bidirectional transmission means, during reproduction, by voltage transmission of one of transmission to the fixed side and transmission to the rotation side of the rotary cylinder and current transmission of the other,
The bidirectional transmission device according to any one of claims 3 to 8 and 11 to 12, wherein the bidirectional transmission is performed simultaneously. 14. The bidirectional transmission means voltage-transmits a signal having a higher minimum frequency and transmits a signal having a lower minimum frequency out of the transmission to the fixed side and the transmission to the rotating side of the rotary cylinder during reproduction. 14. The bidirectional transmission device according to claim 13, wherein the bidirectional transmission device is configured to transmit the current. 15. The bidirectional transmission means performs bidirectional transmission at the same time by performing current transmission in both directions of transmission to the fixed side and rotation side of the rotary cylinder during reproduction. Claims 3-8, 11-11 characterized
13. The bidirectional transmission device according to any one of 12.